Deleading of gasoline



Patented Apr. 18, 1950 DELEADING OF GASOLINE Morris S. Kharasch, Chicago, Ill.,.ass'ignor to the United States of America as represented by the Secretary of the Army No- Drawing. Application May i, 1948, Serial No. 25,091

19 Claims.

The invention described herein, if patented, may be manufactured and used' by 013101 the Government for governmental purposes, without the payment to me off any royalty thereon.

The invention described herein relates to a process for removing tetraethyl'lead. from leaded gasoline, and more particularl to a process in which the leadedgasoline is treated with a per.- hydrohalide. of a tertiary amine to precipitate the tetraethyl lead, and the precipitate then I settled outby treatmentwith'an absorbent substance. such ascharcoal having a. developed internal surface.

Becauseof the fact that most of the. internal combustion engines in use todayare of the highcompression type. and operate more efliciently on fuelof. high-octane.rating,,,the.base stock of most fuels is treated with tetraethyl'lead compounds to increase the octanerating of the fuel. However, certain apparatus of the type used by the armed forces in the field and: by farmers and others, such as low-compression engines, gasoline lanterns and gasoline stoves, does not operate satisfactorily with leaded gasoline because lead'deposits are formed on such vitalparts as valves and burner tips; In many cases, unleaded fuel is-not'readily available to those having need of it, so that amethodi of quickly and inexpensively deleading leaded gasoline is desirable.

Heretofore, several methods have:been.devised for deleading leaded. gasoline, but it has been found that in actual practice these methods do not produce results as satisfactory as desiredrbecause they require too much time, they increase the gum content of the gasoline to an undesirable extent, they removethe dye from the gasoline but very little of the tetraethyl lead, the volume of treating agentrequired relative to the volume ofgasoline deleaded is so large that the methods are impracticable or the gasoline is left with acid constituents or other undesirable constituents.

In one of these methods a relatively small quantity of stannic chloride is mixed with the leaded gasoline. 'Thisrea'ctswith the tetraethyl lead'to form diethyllead" dichloride andpdiethyltln dichloride which being insoluble in gasoline are precipitated; Any stannic chloride in excess of that required to precipitate out the lead isremoved from the gasolineby adding water in order to prevent polymerization. of unsaturated hydrocarbons in the gasoline which would increase the um content-to an undesirable extent. Although this process accomplishes theremoval of tetraethylleadfrom gasoline in a fairly satis- .2 factory manner. it requires a. good. .deal ofitime to complete. a .deleading. operation. and results in. the waste ofiarather largequantity of the asoline being treated. In .addition undesirable acid constituents remain in. the delead'ed gasoline after. treatment.

In my, improved process for deleading. gasoline I initially add to the leaded gasoline. a relatively small quantit of a perhydrohalide of a tertiary m n the perhydrohalide. yields free hydrohalides which .inlturn react with the tetraethyl lead to form. a triethyl. lead halide- The. precipitateis then absorbed. from the gasoline solution by charcoal. The. reaction may be represented by the formulae:

-In order to. provide intimate .contactof the gasoline and-the reactant, it isnecessary to stir or shake themvigorously, say, for-about ten minutes. Inasmuch as most charcoals do not quickly absorb the triethyl lead halide formed by the reaction of the-tetraethyl lead contained in the gasolinewith the perhydrohalide, about 10 hours should be allowed. for the absorption step. After thatitime, the gasoline may be slowly decanted, or preferably passed through a' filter while being drawn off, in order to remove any finev bits of charcoal and/or precipitate which may remain suspended in the solution.

Accordingly, it is an object of the invention to provide anew and. improved process forv re.- moving tetraethyl lead from gasoline in which the tetraethyl lead is' precipitated" from leaded gasoline with a tertiary amine perhydrohalide and the precipitate settled out by adding charcoal-to themixture.

Another object of my-inventionv is the precipitation of tetraethyl lead from gasoline by reacting the former with a hydrogen halide, which is added to the leaded gasoline in chemically bound form.

A. further object of the invention is :the provision of. a new andimproved process for'delea-ding gasoline which is. inexpensive and may be readilycarried out on any desired quantityof gasoline with a minimum of equipment so that the process is adaptable for use. byxthe armed forces in the field or'by'others.desiring gasoline when only leaded gasoline is available.

In. order to disclose the process sufiicientlyto permit the practice .thereof, an example of'a deleading. operation performed. on a. one gallon lot of leaded gasoline will be described. To

one gallon of gasoline substantially free from oleiinic groups containing 2.25 ml./gal. of tetraethyl lead and having a gum content of 8 mg./ ml. are added to 10 ml. of triethylamineperhydrobromide made in accordance with the process described in Example I, and the mixture is shaken at intervals for 10 minutes. 44 g. of Norit A charcoal (a charcoal having a highly developed internal surface) are added, and the mixture is again shaken for ten minutes, and subsequently allowed to stand for about 10 hours. Finally, the charcoal which now has absorbed the precipitated organo-lead is removed by filtration, e. g., by passing the gasoline through a cloth or fine mesh screen. A residue of gasoline should be permitted to remain in the container, as it is likely to be contaminated with charcoal and precipitate remnants. The tetraethyl lead content of the treated gasoline is now only about .26 mL/gal. or slightly more than 10% of the original tetraethyl lead content, the gum content however, increases to about 24-28 mg./100 ml.

The process of the present invention thus produces favorable results with saturated gasolines; however, I have found that when applied to highly unsaturated gasoline (that is, gasoline having a large admixture of olefins), it reduces the tetraethyl lead content appreciably (though not as much as in the case of saturated gasoline),

but has the undesirable tendency of considerably increasing the gum content of the "unsaturated" gasoline. Thus, a gasoline of highly unsaturated gasoline containing 2.25 mL/gal. tetraethyl lead, treated in accordance with the method described in the preceding paragraph, gave a product containing an .89 mL/gal. tetraethvl lead and 385 mg./100 ml. gum. Such a gasoline, while still useful for purposes such as combustion in open burner gasoline stoves, is not particularly desirable in internal combustion engines or other machines where gum deposits would be disadvantageous.

Beside Norit A charcoal, other commercial oharcoals with developed internal surface such as Nuchar, a product of the West Virginia Paper and Pulp Company, may be used. The settling time of about 10 hours after addition of the charcoal is desirable, because shorter settling periods result in appreciably higher organo-lead residues in the treated gasoline, as appears from the following table:

mm Gum Content Time of Standin with Charcoal (ml. tetraethyl g lead/g8 (mg/100 ml.)

Among the perhydrohalides of tertiary amines,

which are found to be useful in the deleading of Several specific examples for the production of tertiary amine perhydrohalides are given below:

Ewample 1 Triethylamine (111.6 g.) is placed in a 500 cc. flask equipped with an inlet tube terminating above the liquid and an exit tube guarded with calcium chloride. The flask is then cooled to C. in a Dry-Ice-acetone bath. Hydrogen bromide is passed into the flask. At first, a solid mass of triethylamine hydrobromide is formed; however, as more hydrogen bromide is added, the solid dissolves. After the solid has vanished, the solution is warmed to room temperature, and the excess hydrogen bromide is allowed to escape. The hydrogen bromide absorbed by the amine amounts to 257 g., or approximately 3 moles of hydrogen bromide per mole of amine. The product triethylamine perhydrobromide is a colorless liquid with an appreciable vapor pressure.

' Example 2 The reaction of Example 1 is carried out with gaseous hydrogen chloride instead of hydrogen bromide. At first, a solid mass of triethylamine hydrochloride is formed, which however, dissolves as more hydrogen is added. After all solids have dissolved, the solution is warmed to room temperature and the excess hydrogen chloride allowed to escape. Approximately 3 moles of hydrogen chloride are taken up by one amine mole. The triethylamine perhydrochloride is a colorless liquid with an appreciable vapor pressure.

, Example 3 The reaction of Example 1 is carried out with tripropylamine (melting point -93.5 C.) and hydrogen bromide as the reagents, in a Dry-Iceacetone bath at about 80 C., and the supply of hydrogen bromide is continued until all tripropylamine monohydrobromide, which initially forms as an intermediary product is dissolved. Tripropylamine perhydrobromide remains in the vessel after the excess hydrogen bromide has been permitted to escape.

The reaction may be represented by the equation wherein R1, R2, and R3 are hydrocarbon radicals, X is a halogen atom, and n is 2 or 3. R1, R2 and R3 may be either identical (as in the case of triethylamine) or non-identical (as in the case of dimethylaniline or allyldiethylamine); however, I have found that trimethylamine does not form a perhydrohalide, and that at least one of the hydrocarbon groups attached to the central nitrogen atom must contain 2 or more carbon atoms.

An excess of the hydrohalide above the stoichiometric proportions represented by the above equation should be used; the excess portion which is not taken up by the tertiary amine is evaporated and may be recovered in the final step of the process. It is desirable that it be carried out at a low temperature, e. g., at about -80 ramps;

*'C.;suchasis providedbyabry rce actonebath.

However, other low temperatures, such-astemlected "as'the "starting material.

Other tertiary iperhydrohal-ides may be formed in the same manner as that'described in the prece'ding examples, by substituting liquid tertiary amines of the general formula ,lRl

those g-i-ven in the-preceding examples. T'I'he temperature of the cooling bath should be higher than the melting point of the amine selected as the starting material. Pyridine does not form a perhydrohalide if treated in accordance with the method described in the specification. Tertiary amines with unsaturated organic radicals, such as allyldiethylamine, take up additional moles of hydrocarbon halide at the double bond; thus allyldiethylamine and an excess of hydrogen bromide or hydrochloride form dibromopropyl diethylamine perhydrobromide, and dichloropropyl diethylamine perhydrochloride, respectively.

Thus:

The reaction products of tertiary amines and excess hydrogen halide are themselves highly reactive because of the ease with which they give up hydrogen halide.

They are thus useful as halogenating agents, and particularly in organo-metallic reactions, such as in the deleading of gasoline.

The above described examples of a method for deleading gasoline are described for the purpose of disclosing the steps to be performed in carrying out a deleading operation in accordance with my improved method. It will be obvious that modifications may be made in the process disclosed without departing from the scope of the invention, hence I do not wish to be limited to the precise process above described but desire to include within the scope of the invention all those modifications included in the claims set forth below.

I claim:

1. The process of deleading gasoline containing tetraethyl lead which comprises adding a perhydrohalide of a tertiary amine to the gasoline and then treating the mixture with charcoal to adsorb the reaction product and settle out the same.

2. The process of deleading gasoline containing tetraethyl lead which comprises adding a perhydrobromide of a tertiary amine to the gasoline and then treating the mixture with charcoal to adsorb the reaction product and settle out the same.

3. The process of deleading gasoline containing tetraethyl lead which comprises adding a perhydrochloride of a tertiary amine to the gasoline and then treating the mixture with charcoal to arisorb' the reaetlon product and. settle out the "same. 1

' The-process'of deleading gasoline containing tetraethylleadwhich-comprises adding a perhydrohal-ide of an allryl amine to the gasoline and then-treating "the mixture with charcoal to ad- "sorbthereaction product and-settle out the'same.

5. The process of deleading gasoline containing tetraethyl l'ead which comprises adding a persame.

6. The process of-del-eadinggasoline containing tetraethyl lead which comprises adding-a perhydrochloride of-ana-lkyl amine to the asoline and then treating the mixture with charcoal to adsorb the reaction product and settle out the same.

7. The process of deleading gasoline containing tetraethyl lead which comprises adding a perhydrohalide of a trialkylamine, said trialkylamine having from 2 to 5 carbon atoms in a chain attached to the nitrogen atom, to the gasoline and then treating the mixture with charcoal to adsorb the reaction product and settle out the same.

8. The process of deleading gasoline containing tetraethyl lead which comprises adding a perhydrobromide of a trialkylamine, said trialkylamine having from 2 to 5 carbon atoms in a chain attached to the nitrogen atom, to the gasoline and then treating the mixture with charcoal to adsorb the reaction product and settle out the same.

9. The process of deleading gasoline containing tetraethyl lead which comprises adding a perhydrochloride of a trialkylamine, said trialkylamine having from 2 to 5 carbon atoms in a chain attached to the nitrogen atom, to the gasoline and then treating the mixture with charcoal to adsorb the reaction product and settle out the same.

10. The process of deleading gasoline containing tetraethyl lead which comprises adding a perhydrohalide of triethylamine to the gasoline and then treating the mixture with charcoal to adsorb the reaction product and settle out the same.

11. The process of deleading gasoline containing tetraethyl lead which comprises adding triethylamine perhydrobromide to the gasoline and then treating the mixture with charcoal to adsorb the reaction product and settle out the same.

12. The process of deleading gasoline containing tetraethyl lead which comprises adding triethylamine perhydrochloride to the gasoline and then treating the mixture with charcoal to adsorb the reaction product and settle out the same.

13. The process of deleading gasoline containing tetraethyl lead which comprises adding to the gasoline a perhydrohalide capable of yielding a hydrogen halide, and then treating the mixture with charcoal to adsorb the reaction product and settle out the same.

14. The process of deleading gasoline containing tetraethyl lead which comprises adding a perhydrobromide capable of yielding hydrogen bromide to the gasoline, and then treating the mixture with charcoal to adsorb the reaction product and settle out the same.

15. The process of deleading gasoline containing tetraethyl lead which comprises adding to the gasoline a perhydrochloride capable of yielding hydrogen chloride, and then treating the mixture with charcoal to adsorb the reaction product and settle out the same.

F 16. The process or deleading gasoline containing a tetraethyl lead which comprises adding about 10 parts by volume of triethylamine perhydrobromide per 2.25 parts by volume of tetraethyl lead contained in said gasoline, agitating said mixture, and treating the mixture with charcoal to adsorb the precipitated organo-metal compound.

17. The process of deleading gasoline containing tetraethyl lead which comprises adding about 10 parts by volume of triethylamine perhydrobromide per 2.25 parts by volume of tetraethyl lead contained in said gasoline, agitating said mixture for about 10 minutes and treating the mixture with charcoal to adsorb the precipitated organo-metal compound.

18. The process of claim 16 wherein the step of treating said mixture with said charcoal has a duration of about 10 hours.

19. The process of claim 1'7, wherein the step of treating said mixture with said charcoal has a 5 duration of about 10 hours.

MORRIS S. KHARASCH.

REFERENCES CITED The following references are of record in the 10 file of this patent:

UNITED STATES PATENTS Number Name Date 2,390,988 Caiingaert et a1. Dec. 18, 1945 15 2,392,846 Friedman Jan. 15, 1946 2,453 138 Kharasch Nov. 9, 1948 

13. THE PROCESS OF DELEADING GASOLINE CONTAINING TETRAETHYL LEAD WHICH COMPRISES ADDING TO THE GASOLINE A PERHYDROHALIDE CAPABLE OF YIELDING A HYDROGEN HALIDE, AND THEN TREATING THE MIXTURE WITH CHARCOAL TO ADSORB THE REACTION PRODUCT AND SETTLE OUT THE SAME. 